1. Field of the Invention
This invention relates to connectors in which components of the connector can be removed for repair or replacement by removing an insert of the connector.
2. Description of Related Art
Recently, a variety of connectors have been developed in which it is possible for the user to remove individual contacts or filter/transient suppression assemblies for repair or replacement in the field, using simple manually operated tools. An example of a repairable transient suppression connector is disclosed in U.S. Pat. No. 4,746,310 (Morse et al.), assigned to Amphenol Corporation. In order to remove the transient suppression components, a removable front insert is provided which, upon removal, affords access to the interior components and enables selective removal of individual transient suppression contact assemblies. The transient suppression contact assemblies each carry a diode which may be replaced without having to replace all of the transient suppression components at once. The insert in the Morse et al. connector is threaded into the connector shell, facilitating removal and yet providing very secure retention of the insert when it is assembled to the connector shell.
The use of a threaded front insert is not possible, however, in certain types of transient voltage suppression and/or filter connectors. For example, the SJT connector, which includes both filters and transient suppression contacts and incorporates features of the scoop proof MIL-C-38999 series I connector into a series II connector, has an extended front interface wall section of specified configuration which is too thin to be threaded and therefore does not allow for the use of a threaded insert. Thus, it has heretofore been impossible to provide an SJT connector which can easily be repaired in the field by manually removing the front insert, despite the advantages that would be possessed by such a connector. The arrangement disclosed by Morse et al. has heretofore also been impossible to implement in connectors which require non-cylindrical front inserts, such as the rectangular ARINC connector. Non-cylindrical connector shells cannot be threaded.
Any removable front insert arrangement for standardized connectors such as the SJT or ARINC connectors must meet three requirements:
1. The insert must be easily removable from the connector shell and yet readily assembled to the connector shell;
2. The insert, when assembled into the connector, must be held securely by the connector shell so as not to unintentionally expose the contents of connector; and
3. Provision for the insert must not require modification of the shell interface, for example by requiring external latches which would interfere with operation of the connector.
In contexts other than connectors, it has previously been proposed to employ frictional locks instead of threading, i.e., locks in which direct engagement between the insert and a housing, or indirect engagement via an additional friction member, is used to secure the insert within the housing. However, the possibility of using a frictional lock in a connector has never been appreciated, primarily because of the necessity of securing the insert within the connector shell when in use. Frictional locks, such as the one disclosed in U.S. Pat. No. 2,841,635 (Witzell), have previously been used only in situations in which a minimum holding force is required, or in conjunction with an additional locking mechanism.
The device disclosed in Witzell is noteworthy because the frictional lock disclosed therein is an O-ring seal which serves to hold a cable coupler cover against movement in one direction relative to a shell when the coupler is not mated with another shell. However, movement in the direction in which tension is likely to be applied is prevented by a separate latch, and thus Witzell-type frictional locks do not appear to be suitable for the purpose of electrical connector insert retention, at least as disclosed in Witzell.
In the context of connector front inserts, O-ring seals have of course long been used, but solely for sealing purposes. For example, the connector of Morse et al. uses an O-ring seal in connection with the above-described removable insert retention arrangement, but does not in any way suggest, explicitly or implicitly, that the O-ring could be arranged to serve as a Witzell-type frictional lock.
The present invention lies in the recognition that, by suitable modification of an electrical connector shell and insert, the O-rings conventionally used as seals between the connector shell and the front insert could also be used to retain the front insert in the connector without affecting the interface, and nevertheless provide a retention force sufficient for all applications of the connector, thus making possible for the first time field repairable SJT-type connectors, as well as field repairable non-cylindrical transient suppression and filter connectors.